Motor driven grinders



June 3, 1958 R. T. CORNELIUS fl 2,

MOTOR DRIVEN GRINDERS Filed April 9, 1956 3 Sheets-Sheet 1 as as 57 FIG. 2

. 2e e4 e2 INVENTOR I g m RICHARD T. CORNELIUS I ATTORNEYS J1me 1958 R. T. CORNELIUS 2,836,937

MOTOR DRIVEN GRINDERS Filed April 9, 1956 5 Sheets-Sheet 2 INVENTOR RICHARD T. CORNELIUS ATTORNEYS R. T. CORNELIUS MOTOR DRIVEN GRINDERS June 3, 1958 5 Sheets-Sheet 3 Filed April 9, 1956 Willi/[IF III,

A I Arl/ I r/ldr/l/r/lli ,3 an 29 1/ wmmmw p a p q 5 r a 1 INVENTOR RICHARD T. CORNELIUS ATTORNEYS MOTOR DRIVEN GRINDERS Richard T. Cornelius, Minneapolis, Minn.

Application April 9, 1956, Serial No. 577,169

9 Claims. (Cl. 51-71) The herein disclosed invention relates to motor driven grinders and has for an object to provide a grinder in which the grindings are prevented from reaching the motor parts and injuring the same.

An object of the invention resides in providing a case having a motor compartment, a blower compartment and a grinding compartment, and in providing a motor mounted in said case in the motor compartment, a blower rotor mounted in the blower compartment and a grinding wheel mounted in the grinding compartment, and in further constructing the case so that the circulation of air caused by the blower rotor passes from the motor compartment and into the grinding compartment.

An object of the invention resides in constructing the case with two partitions forming the three compartments and in providing an inlet passageway from the exterior to the motor compartment, a passageway between the motor compartment and the blower compartment situated in close proximity to the innermost portion of the blower rotor, another passageway between the blower compartment and the grinding compartment, said passageway being situated in proximity to the periphery of the blower rotor, and in further providing a passageway for the air from the grinding compartment and to the exterior.

Another object of the invention resides in providing another passageway between the blower compartment and the grinding compartment situated at the lowermost portion of the grinding compartment to direct air into the grinding compartment at the locality where the grindings are deposited.

Another object of the invention resides in providing a case open at the bottom and in attaching the blower unit and grinding wheel to the motor shaft and inserting the same as a unit into the case through the open bottom thereof.

A still further object of the invention resides in providing slots in the partitions and through which the blower rotor may be inserted into the case and in providing sliding closures adapted to close the slots when the unit is in position.

A feature of the invention resides in making the blower rotor and clamping unit for the grinding wheel integral.

Other objects of the invention reside in the novel combination and arrangement of parts and in the details of construction hereinafter illustrated and/or described.

In the drawings:

Fig. v1 is a plan view of a motor driven grinder illustrating an embodiment of the invention.

Fig. 2 is a fragmentary elevational-sectional View taken on line 2-2 of Fig. l and drawn to a greater scale.

Fig. 3 is a cross-sectional view taken on line 3-3 of Fig. l and drawn to the same scale as Fig. 2.

Fig. 4 is a fragmentary view similar to Fig. 3 and taken on line 44 of Fig. 2. I

Fig. 5 is a longitudinal-sectional view taken on line 5-5 of Fig. 4.

In the form of the invention shown in the drawing two fnited States atent O 'ice grinding units 10 and 11 are employed which are identical in construction except that one is right-handed and one is left-handed. These grinding units are mounted in a single case 12 which contains an electric motor 13 for operating said units. This case is elongated in form, the grinding units 10 and 11 being disposed at the ends of the case and the motor 13 intermediate the grinding units.

Due to the similarity of the units 10 and 11, only the unit 10 will be described in conjunction with the motor 13, it being readily comprehended that the unit 11 is similarly constructed.

The case 12 consists of two longitudinally extending lateral walls 15 and 16 connected together by an arcuate top wall 17. Extending across the walls 15 and 16 is a transverse partition 18. At the ends of walls 15 and 16 is another transverse partition 19 which extends outwardly beyond the walls 16 and 17. This partition has issuing from it a cylindrical wall 21. The case is supported on rubber feet 22 which are attached to flanges 23 extending outwardly from the lower ends of the walls 15 and 16. By means of partitions 18 and 19, the interior of the case 12 is divided to form a motor compartment 24, a blower compartment 25, and grinding compartment 26. The entire case is open at the bottom and the partitions 18 and 19 are formed with slots 27 and 28 therein which open through the lower ends of the same. The compartment 26 is also open at the outer end of the cylindrical wall 21 and at the bottom of the same.

The motor 13 is a conventional construction, being provided with a core 29 having bolted to it by means of bolts 31 brackets 32 in the shape of a crowfoot. These brackets have hubs 33 in which are mounted ball bearings 34. These ball bearings support an armature shaft 35 and on which an armature 36 is mounted. Fans 38 are also mounted on shaft 35 adjacent armature 36. The core 29 has a bore 37 receiving the armature 36 and is provided with the usual windings 38. This construction forming no particular feature of the invention has not been shown in detail in the drawings. The armature shaft 35 has a shaft extension 39 which enters the compartments 25 and 26 of the case 12. Mounted on the shaft extension 39 is a casting 41 which is provided with a radial plate 42 issuing outwardly from a central hub 43. Issuing outwardly from the plate 42 and in the direction of the motor 13 are a number of blades 44 which form in said casting a blower rotor facing the motor 13 and indicated by the reference numeral 40. The slot 28 is of sufiicient dimensions to receive this casting and which projects through said-slot and into the compartment 26.

The plate 42 of casting 41 has a flange 45 forming a continuation of the outer periphery of said plate. Mounted on the shaft extension 39 outwardly of the casting 41 is a grinding wheel 46 which butts up against the flange 45. A collar 47 encircles the shaft extension 39 and engages the opposite side of grinding wheel 46. The ex treme end of the shaft extension 39 is threaded, as indicated at 48, to receive a nut 49 screwed thereon and which clamps the grinding wheel against the casting 41. The casting 41 is held in place by means of a ring 5 which is received in a groove 52 in shaft extension and butts up against a shoulder 53 in the hub 43.

The motor 13 with the two grinding units 1.0 and 11 can be inserted into the case 12 through the open bottom thereof and the parts slid into place through the slots 27 and 28 in the partitions 18 and 19. When properly positioned, the brackets 32 are attached to the walls 15 and 16 of the case by means of screws 54 which are screwed into lugs 55 formed on said brackets. The lowermost portions of the openings 27 and 28 are closed by means of was r) sheet metal closures 56 and 57 which overlie the partitions 18 and 19. These closures are formed with clips 58 and 59 which engage the opposite sides of said partitions and which support the closures for sliding movement into positions as shown in Figs. 2 and 3. The case 12 is closed at the lower portion thereof by means of a sheet metal bottom 61 which is attached to'said case by means of screws 53 screwed into bosses 64 formed at the cor- 11ers between the partition 13 and walls 15 and 16.

The wall 16 of the case is constructed at the lower portion of the same with an opening 65 which forms an inlet passageway to the chamber 24. At this locality the bottom 61 is formed with an upturned flange 62 to stitfen and reinforce the same. The upper end of the slot 27 and the upper end of the closure 56 are constructed to form an opening 66 in the partition 18 and in said closure which is circular in form and concentric with the axis of the shaft 35. This opening forms a passageway bringing chamber 24 into communication with chamber 25 and is of lesser diameter than the periphery of the plate 42 so that air within the compartment 24 is directed to the central portion of the blower rotor 40 and within the confines of the blades 44. The partition 19 and the closure 57 are similarly formed to provide an annular passageway 67 located at the outer periphery of the plate 42 and bringing compartment 25. into communication with compartment 26. In addition, the closure 57 falls short of the bottom 61 to provide another opening 68 in said partition at the lowermost portion of the chambers 25 and 26 and bringing said chambers into communication at said location. The compartment 26 is open at the face thereof which provides a passageway 69 bringing said compartment into communication with the exterior and with another passageway 70 at the lower portion of the same serving the same purpose.

The cylindrical wall 21 is of a diameter to freely receive the grinding wheel 54 at the locality of the wall 15. Both said wall and the partition 19 are cut off flush with wall 15, thus exposing the forward portion 71 of the grinding wheel 54. At this locality a tool rest 72 is employed which is attached to a bracket 73 by means of a bolt 74. The rest 72 may be rotated on said bolt to vary the angle between the supporting surface 75 thereof and the face of the wheel. This bracket, as best shown in Fig. 3, has a slot 76 in the lower portion of the same and through which a bolt 77 extends. This bolt is screwed into a boss 78 formed at the lowermost portion of the wall 15 of case 12. It will readily be comprehended, however, that any type of rest may be used with the invention.

The method of the operation of the invention is as follows:

When the motor 13 is energized, air is drawn into the case by means of the blower 4d and the fans 30. That drawn by the fans 30 circulates through the windings 38 and helps cool the motor proper. That drawn by the blower 40 enters the compartment 24 through the inlet passageway 65, passes about the motor and serves to cool the same and the bearings 34. The air then passes into the compartment 25 through the passageway 66 where the blades 44 throw the air outwardly by centrifugal force. A pressure is created in compartment 25 which forces the air through annular passageway 67 and the passageway 68. This air enters'the compartment 26 and blows any grindings within said compartment in a direction away from the motor 13. Also, the deposit of grindings which occurs at the lowermost portion of the partition 26 is blown outwardly by the air passing through the passageway 68.

The advantages of the invention are manifest. The motor and attached structure is thoroughly cooled so that injury to the same by excess heat is prevented- The air is discharged in such a manner that the same blows into the grinding compartment so as to prevent the grindings from entering either the blower compartment or the motor compartment. In this manner the grindings are kept away from the motor and the life of the motor is greatly increased. The invention can be constructed at a nominal expense and the cost thereof does not greatly exceed that of a conventional grinder.

Changes in the specific form of the invention, as herein described, may be made Within the scope of what is claimed without departing from the spirit of the invention.

Having described the invention, what is claimed as new and desired to be protected by Letters Patent is:

l. motor driven grinder, a case having three compartments arranged in end to end relation, a motor disposed in the innermost of the compartments and secured to said case, said case having an inlet passageway leading from the exterior and into the motor compartment, said motor having a drive shaft extending into said other compartments, a blower rotor attached to said drive shaft and disposed in the intermediate compartment, said case being formed with a passageway between the motor compartment and the blower compartment and directing air to ward the innermost portion of said blower rotor, a grinding wheel attached to the outer end of said motor shaft and'disposed in the outer compartment, said case being formed with a passageway between the blower compartment and the grinding compartment and situated at the outer periphery of said blower rotor and directing air from the blower compartment and into the grinding compartment, said case having a discharge passageway leading from the grinding compartment and to the exterior.

I 2. In a motor driven grinder, a case having three compartments arranged in end to end relation, a motor disposed in the innermost of the compartments and secured to said case, said case having an inlet passageway leading from the exterior and into'the motor compartment,

' said motor having a drive shaft extending into said other compartments, a blower rotor attached to said drive shaft and disposed in the intermediate compartment, said case being formed with a passageway between the motor compartment and the blower compartment and directing air toward the innermost portion of said blower rotor, a grinding wheel attached to the outer end of said motor shaft and disposed in the outer compartment, said case being formed with a passageway between the blower compartment and'the grinding compartment and situated at the outer periphery of said blower rotor and directing air from the blower compartment and into the grinding compartment, said case having another passageway between the blower compartment and the grinding compartment situated at the lowermost portion of the case and directing air into the grinding compartment at the locality of deposit of the grindings, said case having a discharge passageway leading from the grinding compartment and to the exterior.

3. In a motor driven grinder, a case, a motor disposed within and mounted on said case, said motor having an armature and a drive shaft supporting the same, a blower rotor mounted on said drive shaft and having blades on one side thereof extending toward said armature, a grinding Wheel mounted on said drive shaft and. disposed on the other side of and in engagement with said rotor, means on said drive shaft for urging said wheel against said rotor, means in said case forming a passageway leading from the exterior and to said rotor blades, and means in said case forming another passageway directing air circulated by the blades and in a direction away from said armature and against said grinding wheel.

7 4. In a motor driven grinder, a case having two partitions therein permanently attached thereto and dividing the case into three compartments, said case being open at the bottom and said partitions having slots extending from the open end of the case and inwardly, a motor having a core with an armature mounted on a drive shaft rotatable relative to said core, a blower rotor mounted on said drive shaft, a grinding wheel mounted on said drive shaft, said motor, blower rotor and grinding wheel being insertable into said case through the open end thereof and along said slots to bring said motor in one compartment, said blower rotor in another compartment, and said grinding wheel in the last compartment, means for securing said motor to said case and means for conducting air from the motor compartment to the blower compartment and from the blower compartment to the grinding compartment.

5. In a motor driven grinder, a case having two partitions therein permanently attached thereto and dividing the case into three compartments, said case being open at the bottom and said partitions having slots extending from the open end of the case and inwardly, a motor having a core with an armature mounted on a drive shaft rotatable relative to said core, a blower rotor mounted on said drive shaft, a grinding wheel mounted on said drive shaft, said motor, blower rotor and grinding wheel being insertable into said case through the open end thereof and along said slots to bring said motor in one compartment, said blower rotor in another compartment, and said grinding wheel in the last compartment, closures for closing said slots when the motor and attached parts are in position, means for securing said motor to said case and means forming passageways for conducting air from one compartment to the other.

6. In a motor driven grinder, a case having two partitions therein permanently attached thereto and dividing the case into three compartments, said case being open at the bottom and said partitions having slots extending from the open end of the case and inwardly, a motor having a core with an armature mounted on a drive shaft rotatable relative to said core, a blower rotor mounted on said drive shaft, a grinding wheel mounted on said drive shaft, said motor, blower rotor and grinding wheel being insertable into said case through the open end thereof and along said slots to bring said motor in one compartment, said blower rotor in another compartment, and said grinding wheel in the last compartment, closures for closing said slots when the motor and attached parts are in position, means for securing said motor to said case, guide means between said closures and partitions and guiding said closures for movement inwardly along said slots.

7. In a motor driven grinder, a case having a motor compartment and a grinding wheel compartment, a motor disposed in said motor compartment and having a shaft and a rotor supported thereby, said shaft extending into said grinding wheel compartment, a bearing for said shaft disposed adjacent said rotor, a grinding wheel disposed in said grinding wheel compartment and mounted on said shaft, an air impelling rotor mounted on said shaft between said grinding wheel and said bearing and communicating with said grinding wheel compartment, said case having an air inlet directing air into said motor compartment and an air outlet near the periphery of said grinding wheel and directing air out of said grinding wheel compartment, and means in said case forming an air passageway disposed adjacent said bearing and communicating with said motor compartment and said air impelling rotor, said air impelling rotor drawing air through said inlet, into said motor compartment past said bearing, forcing it into said grinding wheel compartment o es? 6 and discharging it from said case through said air outlet.

8. in a motor driven grinder, a case having a motor compartment and a grinding wheel compartment, a motor disposed in said motor compartment and having a shaft and a rotor supported thereby, said shaft extending into said grinding wheel compartment, a bearing for said shaft disposed adjacent said rotor, a grinding wheel disposed in said grinding wheel compartment and mounted on said shaft, a blower rotor mounted on said shaft between said grinding wheel and said bearing and having blades at its periphery drawing air from a locality adjacent said shaft and discharging it at its periphery, said case having an air inlet directing air into said motor compartment and an air outlet near the periphery of said grinding wheel and directing air out of said grinding wheel compartment, and means in said case forming an air passageway disposed adjacent said bearing and communicating with said motor compartment and said blower rotor at its center, means forming an. air passageway communicating with said blower rotor at its periphery and said grinding wheel compartment, said blower rotor drawing air through said inlet, into said motor compartment past said bearing, forcing it through said second named passageway and into said grinding wheel compartment and discharging it from said case through said air outlet.

9. In a motor driven grinder, a case having a motor compartment and a grinding wheel compartment, a motor disposed in said motor compartment and having a shaft and a rotor supported thereby, said shaft extending into said grinding wheel compartment, a bearing for said shaft disposed adjacent said rotor, a grinding wheel disposed in said grinding wheel compartment and mounted on said shaft, a blower rotor mounted on said shaft and adjacent said grinding wheel, said blower rotor being of lesser diameter than said grinding wheel, said case having an air inlet directing air into said motor compartment and an air outlet near the periphery of said grinding wheel and directing air out of said grinding wheel compartment, and means in said case forming an air passageway disposed adjacent said bearing and communicating with said motor compartment and said blower rotor at its center, means forming an annular air passageway leading from the periphery of said blower rotor and to the periphery of said grinding wheel, said blower rotor drawing air through said inlet, into said motor compartment past said bearing, forcing it into said second named passageway to cause the air entering said grinding wheel compartment to flow radially outwardly over the entire exposed lateral area of said grinding wheel adjacent said blower rotor and then longitudinally across the entire peripheral face of the grinding wheel and in a direction away from said bearing.

References Cited in the file of this patent UNITED STATES PATENTS 

